#include <iostream>

using namespace std;

class B;

class A {
    private:
        int m_a;
        int m_b;
    public:
        A(int a=1, int b=2) : m_a(a), m_b(b){}
        friend class B; // 友元类
};

class B {
    public:
        void show(const A &obj) {cout << obj.m_a << "," << obj.m_b << endl;}
};

int main(void)
{
    A a1;
    B b;

    b.show(a1);

    return 0;
}


